Ciliary Body PDT in Pigmented Rabbits using Visudyne and 690 nm Diode Laser

Abstract

Abstract: : Purpose: To evaluate the efficacy of verteporphin (Visudyne) for the induction of transscleral ciliary body PDT in pigmented rabbits. Methods: Visudyne was delivered in 30 pigmented rabbits using bolus i.v. injection in a dose of 1mg/kg. The ciliary body of their right eye was irradiated transsclerally using a 690 nm diode laser (Zeiss, Visulas 690). An optic fiber ending at a rigid probe was used for laser delivery. The laser power was ranging from 10 to 60 mW and the duration of the irradiation from 1 to 5 minutes. Irradiation started 1 minute after the completion of photosensitizer delivery. Three adjacent spots were applied 0.5 mm behind limbus at 12 o'clock position. In 10 control animals laser was applied without photosensitizer injection in order to evaluate its thermal effect. Animals were sacrificed 24 hour after the procedure and their eyes were prepared for histological examination. Results: Based on the results of the control animals a laser power not exceeding 25 mW was used for PDT in order to avoid thermal effect. The irradiation of the ciliary body after the injection of Visudyne resulted in vascular thrombosis of ciliary body vessels. Separation of the two ciliary epithelium layers as a result of epithelial edema was also noted. The effect was localized in the irradiated areas whereas adjacent areas retained their normal architecture. The effect was comparable to the effect that has been described after ciliary body PDT with other photosensitizers. Conclusions: The combination of Visudyne and 690 nm diode laser is effective for the induction of ciliary body photodynamic damage after transscleral PDT. Further investigation is required for the evaluation of the effect duration and of its consequences on IOP.

Keywords: photodynamic therapy • ciliary body